Guidewires are used in various surgical procedures to pilot a device to a desired location in a patient's vascular system. Guidewires, in being a steerable device, are, generally, inserted and maneuvered through the patient's vasculature to a desired location. Once in place, the guidewire provides the means to place a steerless device, such as a catheter, at a chosen site in the patient's vasculature. Guidewires of a standard length are longer than the steerless device to allow for independent movement of the device and the wire.
In balloon angioplasty, one particular surgical application where a guidewire is used, the guidewire is maneuvered to an acute restriction in the patient's cardiovasculature. The piloting of the guidewire is facilitated by a video X-ray device allowing the surgeon to visually observe the movement of the guidewire's distal tip, made of a heavy metal to enhance X-ray viewing.
During a simple angioplasty, the balloon is inflated to open the restriction and then removed along with the guidewire. However, complications do arise which prevent the surgeon from completing this procedure. Sometimes the balloon catheter malfunctions, a larger balloon is required to further dilate the vascular restriction, another device is needed to remove vascular material, etc. The nature of the complication addressed by this invention requires the catheter, or other device, be removed to facilitate placement of another device. In such a situation, the device must be removed and another placed with the assistance of a guidewire.
It is desirable to keep the guidewire in the patient for various reasons. The initial placement of the guidewire requires extensive, time consuming manipulation. Removal and repositioning of the guidewire is equally time consuming requiring additional exposure to drugs, exposure of the patient to additional radiation, and the infliction of additional trauma to the patient.
In those cases where catheter exchange is desired, the surgeon removes the catheter over the guidewire, retaining the guidewire in the patient. To facilitate the removal and replacement of the catheters, the guidewire must be sufficiently long to allow the surgeon to grip a portion of the wire as the catheter is being withdrawn. This requires that the guidewire be long enough to provide an external portion longer than the catheter. However, a guidewire of such length has inferior handling characteristics adding significant difficulty to steering and maneuvering related manipulations. The added length also imposes itself on a usually cramped operating environment causing distractions to other surgical support activities. It is for this reason that guidewires are usually only slightly longer than the typical balloon catheter, e.g. 20-50 centimeters. In one previous method of catheter exchange, the original guidewire is replaced with a longer guidewire, after which the catheter is exchanged. This approach proved to be tedious.
A more recent development involves coupling a second length of wire to the exposed, proximal guidewire end. The second wire length should be of sufficient length to allow the catheter to be withdrawn while retaining the guidewire in the patient. Various approaches have been suggested for effecting the attachment of this added length.
In one approach, two wires are joined together by crimping which requires a special tool. Once the wires have been crimped, the connection therebetween is permanent, and the extension wire cannot be removed except by severing it from the guidewire. Instead of crimping, some attempts have tried to frictionally engage the extension wire to the guidewire. While frictional engagement overcomes the need to crimp, disengagement may still occur. Moreover, prior extendable wires for use in coronary angioplasty procedures have been found to be unsuitable in peripheral arteries because the connections are not strong enough and may disengage.
In another approach, the extension wire is twisted onto the guidewire. This requires that the entire wire be twisted. This can be cumbersome due to the length of the wire.
In still another approach, the guidewire is threaded into a bolt which is attached to the extension wire by means of a ball and socket swivel mechanism. The extension or guidewire do not need to be rotated to effect an attachment. The ball and socket mechanism, however, sacrifices pushability and flexibility as the ball and socket joint do not effect a mechanical lock sufficient to transmit such desirable properties.
Further, some connections are made at larger diameters than the rest of the guidewire system which may cause snagging of the catheter. A guidewire system having varying diameters requires a catheter, which is being passed over the guidewire, to have a larger internal diameter than would be necessary to fit over the smaller guidewire diameter.
Accordingly, a principal object of the present invention is to provide a guidewire extension system which is easy to use and easy to manufacture. It is a further object of the present invention to provide a guidewire extension system which minimizes the possibility of system failure by kinking or undesirable bending at the connection between the guidewire and the extension wire. Another object of the present invention is to provide a guidewire extension system utilizing a turnbuckle configuration which does not require that either the guidewire or extension wire be twisted. It is advantageous that the guidewire be held stationary because the guidewire is located within the patient's blood vessel where movement induces trauma. It is also advantageous to have the extension wire stationary and partially coiled in its package. Having the extension wire self-contained allows the operator to concentrate on engaging the two wires, whereas an unpackaged extension wire is awkward requiring additional attention thus complicating the logistics involved in effecting a union.
It is still a further object of the present invention to provide a guidewire extension system which has substantially the same flexibility and pushability at the connection as results with the standard guidewire.
Another object of the present invention is to provide a guidewire extension system using a threaded-type engagement such as that which results from applying helically twisted wires and a tube to fashion a turnbuckle nut. Such a turnbuckle nut provides a simple design to manufacture.
A further object of one embodiment of the present invention is to provide a guidewire extension system having bolt elements on the guidewire and on the extension wire which avoids the necessity of machining threaded bolts at the end of the guidewire and extension wire affording a simple design to manufacture.
It is yet another object of the present invention to provide a unitized guidewire extension system having a uniform, smooth, continuous outer diameter along the guidewire, connector, and extension wire.